This application claims the priority of German Application No. 102 61 011.8 filed Dec. 17, 2002, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for producing a spun thread from a staple fiber mass, comprising a feed channel having an outlet opening for feeding the staple fiber mass, a stationary, spindle-shaped component arranged downstream of the outlet opening having a yarn withdrawal channel comprising an inlet opeing, a vortex chamber connected to compressed air nozzles and located between the outlet opening and the inlet opening for generating a rotating current around the inlet opening, an air evacuation duct surrounding, essentially ring-like, the spindle-shaped component, and fiber guiding surfaces deflecting the staple fiber mass for forming a twist block.
An arrangement of this type is prior art in European published patent 854 214. In this arrangement, a staple fiber mass, leaving a drafting unit, is guided through a feed channel to the inlet opening of a yarn withdrawal channel, whereby initially the front ends of the fibers contained in the staple fiber mass are guided into the yarn withdrawal channel, while the free rear fiber ends are spread apart and seized by the rotating current and twisted around the already bound-in front ends located in the inlet-opening of the yarn withdrawal channel, thus generating a thread having to a great extent a real twist.
Around the area of the inlet opening, a regular “sun” is formed by the circling fibers due to the rotating air current, some of which fibers are also wound around the spindle-shaped component.
In the case of the known arrangement, helical-shaped fiber guiding surfaces are provided as twist blockers, whereby the helix has the same direction of rotation as the rotating air current and extends over a peripheral angle of between 90° and 120°. The helix is formed by means of an insert in a tube and thus fills out approximately half the cross section of the tube, whereby the remaining empty area of the cross section forms the feed channel. The fibers of the staple fiber mass are disposed continuously in the feed channel on this helix.
It is an object of the present invention to increase and intensify the action of the twist block in a system of the above referred to type.
This object is achieved in accordance with certain preferred embodiments of the present invention in that the feed channel extends in a meandering manner, and in that the fiber guiding surfaces are designed as deflecting edges, between which the staple fiber mass is without any support.
Because of the meandering extent of the feed channel and because of the deflecting edges, which can be of any number, a very effective twist block is achieved, which develops gradually from a zero effect to a very intensive twist block. Because the staple fiber mass is without any support between the deflecting edges, fibers can loosen and spread out in these areas so that at a later stage in the vortex chamber, they are available as circulating fibers around the core fibers.
According to certain preferred embodiments of the present invention, it is provided that the last deflecting edge in the travel direction of the staple fiber mass is arranged eccentrically to the inlet opening of the yarn withdrawal channel. This increases the effect of the last deflecting edge, in particular when this is arranged in direct proximity to the inlet opening of the yarn withdrawal channel.
According to certain preferred embodiments of the present invention, in order to keep the twist block as compact as possible, only three deflecting edges are provided.
According to certain preferred embodiments of the present invention, it can be provided that at least one deflecting edge is additionally provided with a profile. The effect of the twist block can thus be intensified even further. In the case of said profile, at least one wedge-shaped groove, arranged in travel direction of the staple fiber mass can be involved, by means of which the individual fibers of the staple fiber mass separate and are nipped in a certain way. Alternatively, a plurality of very small notch-like grooves can provided, which serve the same purpose.